1. Unmark the 07 and 08 tests of block_attach as XFAIL

1. Unmark the 07 and 08 tests of block_attach as XFAIL
2. Change the MEM_PER_DOM amount in 11_create_concurrent to 24MB, so
   that the test will run on x86_64.
3. Increase the number of DomUs created in 12_create_concurrent to 5
4. Fix a logic error in 01_unpause
5. Add a test 06_help that checks all xm commands with 0-10 arguments
   to make sure none of them traceback with varying argument counts.

Signed-off-by: Dan Smith <danms@us.ibm.com>